1. Technical Field
This invention relates to thermal management of a personal computer. More specifically, the thermal management applies to detection of movement of a personal computer from a stationary surface and managing cooling of heat generating components in response to the movement.
2. Description of the Prior Art
It is known in the art that electronic parts in computer systems generate heat. Fans and heat sinks have been developed to manage heat dissipation of electronic parts. Laptop computers are a category of personal computers that are relatively compact and, as such, are portable. However, problems arise when a user of a laptop computer moves the laptop from a stationary position on a stationary surface, to their lap or another part of their body. The problems that arise are found in excess heat reaching the surface of the body of the user through a base surface of the computer, which can cause discomfort. Accordingly, there is a need to accurately detect movement from a stationary surface and to efficiently dissipate heat from the computer components so that a user of the laptop will not suffer discomfort.
There are several patents that address thermal management of a laptop computer. For example, U.S. Pat. No. 6,760,649 to Cohen provides a pressure sensor on a base cover of a laptop computer to determine whether the base surface of the laptop is in direct contact with a lap of the user and to initiate a cooling function in response to activation of the pressure sensor. When the laptop is on a stationary surface, the pressure sensor does not become activated since the sensor has consideration for a gap frequently formed between the base surface of a laptop casing and a resting surface, such as a stationary surface. As such, the pressure sensor does not activate on a stationary surface. However, there are limitations associated with the '649 patent to Cohen. For example, an erroneous determination may arise when the user of the laptop is not in direct contact with the base surface of the casing. One such example is if an object becomes caught between the casing and stationary surface, or an edge of the stationary surface is detected as a lap when a portion of the casing is placed into a position to jut out from the stationary surface without support. Activation of the sensor results in initiation of cooling measures, which in turn results in an increase in fan noise and may result in lowering the frequency of the processor clock. Cooling measures which lower the frequency of the processor clock affect the performance of the personal computer. If the cooling measures are initiated in response to a false reading of a sensor, then the personal computer may inappropriately operate at a lower performance level. Accordingly, the prior art does not address the need for an accurate tool for detecting movement of a laptop from a stationary surface.
Therefore, there is a need for an accurate method of determining when a laptop computer has been moved from a stationary surface to a lap of a user or other part of the body. The method should include the entire surface area of the base surface of the laptop, and restrictively respond to the movement with a minimal thermal management adjustment so that the adjustment should not interfere with internal or external operations of the computer.